The blast occurred on the tree-lined avenue in the center of the capital, Tunis. The explosion came 10 days after authorities increased the security level in the capital and deployed security forces in unusually high numbers.

Earlier this month, Tunisian authorities announced the dismantling of a cell it said had planned terror attacks at police stations and hotels in the seaside city of Sousse, about 95 miles southeast of Tunis.

Tunisia’s tourism industry has been hit hard this year following extremist attacks.

Shootings at a luxury beach hotel in Sousse last June killed 38 people, mostly tourists, while in March an attack by Islamist extremists at Tunisia’s famed Bardo museum near the capital killed 22 people.